What is Free Evolution?
Free evolution is the concept that natural processes can lead to the development of organisms over time. This includes the development of new species and change in appearance of existing species.
This is evident in numerous examples of stickleback fish species that can live in fresh or saltwater and walking stick insect varieties that are apprehensive about particular host plants. These mostly reversible traits permutations do not explain the fundamental changes in the basic body plan.
Evolution through Natural Selection
The development of the myriad living creatures on Earth is a mystery that has intrigued scientists for many centuries. The most widely accepted explanation is that of Charles Darwin's natural selection, which occurs when better-adapted individuals survive and reproduce more successfully than those that are less well adapted. Over time, the population of well-adapted individuals becomes larger and eventually creates an entirely new species.
Natural selection is a cyclical process that involves the interaction of three elements that are inheritance, variation and reproduction. Sexual reproduction and mutation increase the genetic diversity of an animal species. Inheritance refers to the passing of a person's genetic characteristics to their offspring which includes both recessive and dominant alleles. Reproduction is the generation of fertile, viable offspring which includes both asexual and sexual methods.
Natural selection is only possible when all these elements are in equilibrium. For example, if an allele that is dominant at a gene can cause an organism to live and reproduce more frequently than the recessive one, the dominant allele will become more common within the population. If the allele confers a negative advantage to survival or reduces the fertility of the population, it will be eliminated. The process is self reinforcing, which means that an organism with an adaptive characteristic will live and reproduce far more effectively than those with a maladaptive feature. The more offspring an organism can produce the better its fitness which is measured by its ability to reproduce itself and survive. Individuals with favorable traits, such as longer necks in giraffes, or bright white colors in male peacocks are more likely to survive and produce offspring, and thus will make up the majority of the population over time.
Natural selection is a factor in populations and not on individuals. This is a significant distinction from the Lamarckian theory of evolution, which states that animals acquire characteristics through use or neglect. For instance, if a giraffe's neck gets longer through stretching to reach for prey its offspring will inherit a longer neck. The differences in neck size between generations will increase until the giraffe is unable to breed with other giraffes.
Evolution through Genetic Drift
In the process of genetic drift, alleles within a gene can attain different frequencies in a group by chance events. In the end, only one will be fixed (become common enough that it can no more be eliminated through natural selection) and the rest of the alleles will diminish in frequency. 에볼루션 바카라 무료 can result in a dominant allele in extreme. The other alleles are essentially eliminated and heterozygosity has decreased to a minimum. In a small group it could lead to the complete elimination of recessive alleles. This scenario is called the bottleneck effect. It is typical of an evolutionary process that occurs whenever the number of individuals migrate to form a population.
A phenotypic bottleneck could occur when survivors of a disaster such as an epidemic or mass hunting event, are condensed into a small area. The remaining individuals will be mostly homozygous for the dominant allele, which means they will all share the same phenotype and will consequently have the same fitness characteristics. This could be the result of a war, earthquake or even a cholera outbreak. The genetically distinct population, if it is left susceptible to genetic drift.
Walsh Lewens, Walsh and Ariew define drift as a departure from the expected value due to differences in fitness. They give the famous example of twins who are both genetically identical and share the same phenotype, but one is struck by lightning and dies, while the other is able to reproduce.
This type of drift is vital to the evolution of a species. It is not the only method of evolution. The main alternative is a process known as natural selection, in which the phenotypic diversity of the population is maintained through mutation and migration.
Stephens claims that there is a vast distinction between treating drift as a force or cause, and treating other causes such as migration and selection mutation as forces and causes. He claims that a causal-process model of drift allows us to differentiate it from other forces and that this distinction is crucial. He argues further that drift is both a direction, i.e., it tends to reduce heterozygosity. It also has a size which is determined by population size.
Evolution by Lamarckism
In high school, students study biology, they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, commonly referred to as "Lamarckism is based on the idea that simple organisms develop into more complex organisms by taking on traits that result from the organism's use and misuse. Lamarckism can be demonstrated by an giraffe's neck stretching to reach higher levels of leaves in the trees. This would cause giraffes to give their longer necks to their offspring, who then grow even taller.
Lamarck was a French Zoologist. In his opening lecture for his course on invertebrate Zoology at the Museum of Natural History in Paris on the 17th May 1802, he presented a groundbreaking concept that radically challenged the previous understanding of organic transformation. According to Lamarck, living things evolved from inanimate material through a series of gradual steps. Lamarck was not the only one to suggest that this could be the case, but the general consensus is that he was the one giving the subject its first general and thorough treatment.
The most popular story is that Charles Darwin's theory of natural selection and Lamarckism were rivals during the 19th century. Darwinism eventually triumphed, leading to the development of what biologists today refer to as the Modern Synthesis. This theory denies acquired characteristics can be passed down through generations and instead argues that organisms evolve through the selective influence of environmental elements, like Natural Selection.
Lamarck and his contemporaries endorsed the notion that acquired characters could be passed on to future generations. However, this concept was never a central part of any of their theories about evolution. This is partly due to the fact that it was never validated scientifically.
It's been more than 200 years since Lamarck was born and in the age of genomics there is a vast amount of evidence that supports the possibility of inheritance of acquired traits. This is sometimes called "neo-Lamarckism" or, more frequently, epigenetic inheritance. This is a version that is as valid as the popular neodarwinian model.
Evolution by Adaptation
One of the most popular misconceptions about evolution is its being driven by a struggle for survival. This view is a misrepresentation of natural selection and ignores the other forces that are driving evolution. The fight for survival can be more precisely described as a fight to survive within a particular environment, which can involve not only other organisms, but also the physical environment.
To understand how evolution works it is beneficial to understand what is adaptation. It is a feature that allows a living thing to survive in its environment and reproduce. It could be a physical structure such as feathers or fur. It could also be a behavior trait such as moving to the shade during the heat, or coming out to avoid the cold at night.
The capacity of an organism to draw energy from its surroundings and interact with other organisms and their physical environments is essential to its survival. The organism must have the right genes to produce offspring, and it should be able to access enough food and other resources. The organism must also be able reproduce itself at the rate that is suitable for its particular niche.
These elements, along with gene flow and mutations, can lead to changes in the proportion of different alleles within a population’s gene pool. Over time, this change in allele frequencies could result in the development of new traits, and eventually new species.
A lot of the traits we admire in plants and animals are adaptations. For example lung or gills that extract oxygen from the air feathers and fur as insulation long legs to run away from predators and camouflage for hiding. However, a proper understanding of adaptation requires attention to the distinction between behavioral and physiological characteristics.
Physical traits such as thick fur and gills are physical characteristics. The behavioral adaptations aren't, such as the tendency of animals to seek companionship or retreat into shade in hot weather. It is important to note that insufficient planning does not cause an adaptation. Inability to think about the effects of a behavior even if it seems to be rational, may make it unadaptive.